Presentation on theme: "I. Physical Properties Ch. 12 - Gases. A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume have elastic collisions are in constant,"— Presentation transcript:
A. Kinetic Molecular Theory b Particles in an ideal gas… have no volume have elastic collisions are in constant, random, straight- line motion dont attract or repel each other have an avg. KE directly related to Kelvin temperature
B. Real Gases b Particles in a REAL gas… have their own volume attract each other b Gas behavior is most ideal… at low pressures at high temperatures in nonpolar atoms/molecules
C. Characteristics of Gases b Gases expand to fill any container random motion, no attraction b Gases are fluids (like liquids) no attraction b Gases have very low densities no volume = lots of empty space
C. Characteristics of Gases b Gases can be compressed no volume = lots of empty space b Gases undergo diffusion & effusion random motion
D. Temperature ºF ºC K -45932212 -2730100 0273373 K = ºC + 273 b Always use absolute temperature (Kelvin) when working with gases.
E. Pressure Which shoes create the most pressure?
E. Pressure b Barometer measures atmospheric pressure Mercury Barometer b exact height of the Hg depends on atmospheric pressure b usually measured in mm Hg
E. Pressure b Manometer measures contained gas pressure U-tube Manometer b Difference in height in two arms of U- tube is measure of pressure of gas sample b measured in various different units
E. Pressure b KEY UNITS AT SEA LEVEL 101.325 kPa (kilopascal) 1 atm 760 mm Hg 760 torr 14.7 psi
F. STP Standard Temperature & Pressure 0°C 273 K 1 atm101.325 kPa -OR- STP
G. Pressure Problem 1 b The average pressure in Denver, Colorado, is 0.830 atm. Express this in (a) mm Hg and (b) kPa. (a) 0.830 atm 1 atm 760 mm Hg = 631 mm Hg (b) 0.830 atm 1 atm 101.325 kPa = 84.1 kPa
G. Pressure Problem 2 b Convert a pressure of 1.75 atm to kPa and mm Hg. (a) 1.75 atm 1 atm 101.325 kPa = 177 kPa (b) 1.75 atm 1 atm 760 mm Hg = 1330 mm Hg
G. Pressure Problem 3 b Convert a pressure of 570. torr to atmospheres and kPa. (a) 570 torr 760 torr 1 atm =.750 atm (b) 570 torr 760 torr 101.325 kPa = 76.0 kPa